The present invention relates to an oil tensioner, wherein oil is contained in an oil chamber which is formed by a housing and a plunger therebetween.
FIG. 6 shows a sectional view of a conventional oil tensioner. As shown in FIG. 6, such a tensioner 50 includes a housing 54, having an aperture therewithin, and a plunger 56, slidably reciprocating within the aperture, wherein oil is contained in an oil chamber 60 which is formed within the aperture by a housing 54 and a plunger 56 therebetween. The plunger 56 is biased by external oil hydraulics and spring 62, which in turn gives power transmission members, such as chain and belt, tensile strength.
In such a tensioner 50, it has been thought of as preferable to make a sliding surface between the housing 54 and the plunger 56 a mirror finished surface in order that the plunger 56 to smoothly slide therebetween.
However, it has been discovered that as the sliding distance of the plunger 56 with respect to the housing 54, or displacement of the plunger 56 while the tensioner 50 is operating, gets very little, face pressure between the housing 54 and the plunger 56 becomes larger, thereby causing a seizure phenomenon in case of working a mirror finished surface on the sliding surface thereof.